The present invention relates generally to surgical retrieval instruments and relates more specifically to a stone basket or medical retrieval device in which the basket can be articulated.
Medical retrieval devices or stone baskets for capturing and extracting stones from ureters are well known. Such instruments typically comprise a basket at the forward end of an elongated sheath. Wires disposed within the sheath connect the basket to a handle at the opposite end of the sheath. Various mechanisms for expanding and contracting the basket may be associated with the handle.
Today""s stone baskets are being used for purposes other than simply capturing a stone in a ureter. They must also be able to reach the kidney, capture a stone, reposition it, remove it, or hold it for adjunctive treatment. Larger baskets can capture larger stones but perform poorly in capturing smaller stones. Known medical retrieval devices cannot readily release a stone if complications arise and there is a need to exit quickly. On occasion, a physician may actually have to cut the basket wires in order to release a stone, which presents the obvious complication of having to extract the basket wires from the patient.
Many conventional medical retrieval devices have tips at their forward ends for joining the legs of the basket. Such xe2x80x9ctippedxe2x80x9d medical retrieval devices usually have to be maneuvered alongside the stone to permit the stone to enter the basket laterally. Tipped medical retrieval devices thus present special challenges when a stone is located directly ahead of the basket and lodged against an obstruction, such as the wall of a kidney, which prevents the basket from being maneuvered alongside the stone.
Stated generally, the present invention comprises a medical retrieval device. The device includes a handle, two gear racks movably mounted to the handle for longitudinal movement, and a pinion rotatably mounted to the handle so as to engage the two gear racks. Rotation of the pinion moves the gear racks in opposite directions. A basket has at least three legs, an adjacent two of the legs being connected to one of the gear racks, and the remainder of the legs being connected to the other gear rack such that rotation of the pinion displaces the two legs in a first direction and displaces the remainder of the legs in a second direction. Thus rotation of the pinion articulates the basket.
In one embodiment of the invention a sheath extends from the front of the handle, and the basket is located at the forward end of the sheath. A slide is mounted to the handle for longitudinal movement, and the gear racks and pinion are mounted to the slide. Movement of the slide extends or retracts the basket with respect to the sheath.
In another embodiment of the invention the sheath is coupled to the slide and extends or retracts as the slide is translated. The gear racks and pinion are mounted to the handle at a longitudinally fixed position. Rotation of the pinion articulates the basket, while translation of the slide moves the sheath to cover or expose the basket.
In the disclosed embodiments the slide assembly is moved along its longitudinal path by the operator applying pressure with his thumb to a button on the top of the slide assembly. Also in the disclosed embodiments, a thumb wheel is operatively associated with the pinion such that rotation of the wheel by the operator""s thumb causes the pinion to rotate to articulate the basket.
In another aspect the invention relates to a basket for a medical retrieval device and to a method for manufacturing the basket. The basket has the forward ends of its legs mounted to a tip member. In one embodiment the tip member has a hole, the forward ends of the tip members are inserted into the hole, and the tip member is crimped to clamp the legs to the tip member.
A special feature of the disclosed embodiments is the capability of a tipped basket to articulate to such a degree that the tip is moved to a location rearward of the forward extent of the basket. This capability permits the basket to open forwardly to permit an object directly ahead of the basket to enter the basket without having to maneuver the basket alongside the stone. Thus stones which are lodged against an obstruction such as the wall of a kidney which could normally not be retrieved with a tipped basket can be retrieved with the medical retrieval device of the disclosed embodiment.
Another special feature of the disclosed embodiment is that, after having grasped a stone, the basket is capable of releasing it. Thus if a physician begins to withdraw a stone and finds it is too large to pass through a physiological constriction such as the intramural ureter, or if complications arise which require rapid extraction of the medical retrieval device, the physician can articulate the basket to spread the basket wires, thereby releasing the stone.